Differential assembly

ABSTRACT

An axle assembly that includes a differential casing, which is rotatable about an axis, a pair of side gears that are disposed within the differential casing, a spacer and a cross pin. The spacer is disposed between the side gears. The cross pin is fixed to the differential casing and extends through the spacer. The cross pin is employed to limit end play of the axle shafts in a direction toward one another. The aperture in the spacer that receives the cross pin is relatively larger than the cross pin so that the spacer can control end play of the side gears independently of the cross pin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/343,855filed Jan. 31, 2006, which is a continuation of U.S. patent applicationSer. No. 10/794,780 filed Mar. 5, 2004, now issued U.S. Pat. No.7,022,041. The disclosures of the above applications are incorporatedherein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to differentials for use in automotivedrivelines and, more particularly, to a pinion pair arrangement for afour pinion pair, C-clip differential having independent control of sidegear endplay and axle shaft endplay.

BACKGROUND OF THE DISCLOSURE

Differentials of the type used in automotive drivelines generallyinclude a planetary gearset supported within a differential casing tofacilitate relative rotation (i.e., speed differentiation) between apair of output shafts. The planetary gearset typically includes helicalside gears fixed to the end of the output shafts, which are meshed withpaired sets of helical pinion gears. This type of differentiation isknown as a parallel axis helical gear differential. In response to inputtorque applied to the differential case, the torque transmitted throughmeshed engagement of the side gears and pinion gears generates thrustforces. To accommodate these and other operating forces, the wallsurface of the gear pockets and other thrust surfaces of thedifferential casing must provide adequate support.

In some differentials it is necessary to install C-shaped retainers, orC-clips for restraining and positioning the output shafts in thedifferentials. To install the C-clips it is necessary to gain access tothe interior cavity of the differential casing through an access windowarranged on the differential casing.

In general, it is desirable to allow the side gear loading to be spreadout evenly around the periphery of the differential. One way to achieveeven loading is to position the pinion pairs evenly around the peripheryof the differential casing. However, because the access window isarranged on the outer periphery of the differential casing, there tendsto be incompatibility issues with placement of the pinion pairs.

SUMMARY OF THE DISCLOSURE

In one form, the present disclosure provides an axle assembly for avehicle that includes a differential casing, a pair of side gears, apair of axle shafts, a spacer and a cross pin. The differential casingis rotatable about an axis and includes a first pin aperture. The sidegears are disposed within the differential casing. Each axle shaft iscoupled for rotation with one of the side gears. The spacer is disposedbetween the side gears and has a second pin aperture. The cross pin isreceived into the first and second pin apertures such that receipt ofthe cross pin into the first pin aperture fixedly but removably couplesthe cross pin to the differential casing. The size of the second pinaperture is greater than a corresponding size of the cross pin such thatthe spacer is moveable along the rotational axis of the differentialcasing relative to the cross pin. As such, the cross pin limits movementof the axle shafts in a direction toward one another and the spacerlimits movement of the side gears toward one another independently ofthe cross pin.

In another form, the present disclosure provides a method that includes:providing a differential casing having a rotational axis; installing apair of side gears within the differential casing; installing a pair ofaxle shafts to the side gears such that each axle shaft is coupled forrotation with one of the side gears; locating a spacer between the sidegears; fixedly coupling a cross pin to the differential casing such thatthe cross pin is inserted through a pin aperture in the spacer; andmoving the side gears and the spacer in a first direction along therotational axis without moving the cross pin.

In yet another form, the present disclosure provides an axle assemblyfor a vehicle that includes a differential casing, a pair of side gears,a pair of axle shafts, a spacer and a cross pin. The differential casingis rotatable about an axis and includes a first pin aperture. The sidegears are disposed within the differential casing. Each axle shaft iscoupled for rotation with one of the side gears. The spacer is disposedbetween the side gears and includes a second pin aperture. The cross pinis received into the first and second pin apertures. Receipt of thecross pin into the first pin aperture fixedly but removably couples thecross pin to the differential casing. The size of the second pinaperture is greater than a corresponding size of the cross pin such thata void space is disposed between the spacer and the cross pin regardlessof a position of the side gears axially along the rotational axis.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the disclosure, are intended forpurposes of illustration only and are not intended to limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic view of an exemplary motor vehicle into which adifferential assembly constructed in accordance with the teachings ofthe present disclosure is incorporated;

FIG. 2 a is a perspective view of the differential assembly of FIG. 1;

FIG. 2 b is a perspective view of the differential casing of FIG. 1;

FIG. 3 is an exploded view of the differential assembly of FIG. 1;

FIG. 4 is a cross-sectional view of the differential assembly takenalong line 4-4 of FIG. 2 a;

FIG. 5 is a cross-sectional view of the differential assembly takenalong line 5-5 of FIG. 4;

FIG. 6 is a perspective view of the differential assembly of FIG. 1illustrating the cross pin assembly in an exploded condition;

FIG. 7 is a perspective view of the differential assembly of FIG. 1illustrating the cross pin assembly engaged to the cylindrical boss ofthe differential casing;

FIG. 8 is a perspective view of the differential assembly of FIG. 1illustrating the cross pin assembly in an installed condition;

FIG. 9 is an exploded view of a differential assembly according to otherfeatures;

FIG. 10 is an exploded view of a differential assembly according toother features; and

FIG. 11 is an exploded view of the differential assembly according toother features.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the disclosure,its application, or uses. The differential assembly according to thepresent teachings may be utilized with a wide variety of applicationsand is not intended to be specifically limited to the particularapplication recited herein.

With initial reference to FIG. 1, a drivetrain 10 for an exemplary motorvehicle may include an engine 12, a transmission 14 having an outputshaft 16, and a propeller shaft 18 connecting the output shaft 16 to apinion shaft 20 of a rear axle assembly 22. The rear axle assembly 22includes an axle housing 24, a differential assembly 26 supported in theaxle housing 24, and a pair of axle shafts 28 and 30, respectively,interconnected to a left and right rear wheel 32 and 34, respectively.The pinion shaft 20 has a pinion shaft gear 36 fixed thereto whichdrives a ring gear 38 that may be fixed to a differential casing 40 ofthe differential assembly 26. A gearset 42 supported within thedifferential casing 40 transfers rotary power from the casing 40 to apair of output shafts 44 and 45 connected to the axle shafts 28 and 30,respectively, and facilitates relative rotation (i.e., differentiation)therebetween. While the differential assembly 26 is shown in arear-wheel drive application, the present invention is contemplated foruse in differential assemblies installed in transaxles for use infront-wheel drive vehicles, and/or in transfer cases for use infour-wheel drive vehicles.

Turning now to FIGS. 2 a-4, the differential assembly 26 will bedescribed in further detail. The differential assembly 26 may be aparallel-axis helical-gear type differential and includes thedifferential casing 40, which defines an internal chamber 48. Thedifferential casing 40 includes a main drum or body 46 and an end cap50, each of which having respective mating radial flanges 52 and 54,respectively. The radial flanges 52 and 54 are secured together by aplurality of bolts (not shown) extending through aligned mounting bores58. As is known, a ring or bevel gear can be fixed to the radial flange52 on the differential casing 40 to transfer rotary power (i.e., drivetorque) thereto. The differential casing 40 defines a pair of axiallyaligned openings 60 a and 60 b in communication with the internalchamber 48. The axially aligned openings 60 a and 60 b are adapted toreceive the end segments of the pair of driving output shafts 44 and 45(FIG. 1), also referred to as axle shafts.

With specific reference to FIGS. 3 and 4, the differential assembly 26includes the gearset 42 that is operable for transferring drive torquefrom the differential casing 40 to the output shafts 44 and 45 (FIG. 1)in a manner that facilitates a speed differential therebetween. Gearset42 may be a helical-type and may be disposed within the internal chamber48. The gearset 42 includes a pair of side gears 68 a and 68 b. The sidegears 68 a, 68 b have internal splines 70 a and 70 b meshed withexternal splines, not specifically shown, on the corresponding outputshafts 44 and 45 (FIG. 1). In addition, the side gears 68 a and 68 binclude axial hubs 78 a and 78 b, respectively, which are retained incorresponding annular sockets, formed in the main body 46 and the endcap 50 of the differential casing 40, and annular chambers 82 a and 82b. As will be described in greater detail below, a spacer 86 may belocated between the side gears 68 a and 68 b for limiting the amount ofaxial endplay of the side gears 68 a and 68 b within the differentialcase 40. A cross pin assembly 90 extends through a clearance passage 92in the spacer 86 and controls endplay of the axle shafts 44 and 45 (FIG.1).

C-shaped retainers, or C-clips 94, may be retained in the annularchambers 82 a and 82 b for preventing the axle shafts 44 and 45,respectively, from becoming disengaged with the side gears 68 a and 68b. The side gears 68 a and 68 b may be bounded at their outer ends bywashers 96.

The gearset 42 includes four sets of pinion pairs, 100 a and 100 b, 102a and 102 b, 104 a and 104 b and 106 a and 106 b, respectively (FIG. 3).For clarity the pinion pairs 100 a and 100 b, 102 a and 102 b, 104 a and104 b and 106 a and 106 b are hereinafter referred to as a first,second, third and fourth pair of pinion gears 100, 102, 104 and 106,respectively. Brake shoes 100 a′-106 b′ cooperate with respective piniongears 100-106.

In FIGS. 2 b and 3, the four sets of pinion pairs 100-106 are rotatablysupported in complementary sets of pinion bores 110 a and 110 b, 112 aand 112 b, 114 a and 114 b, and 116 a and 116 b. The complementary setsof pinion bores 110 a and 110 b, 112 a and 112 b, 114 a and 114 b, and116 a and 116 b are hereinafter referred to as a first, second, thirdand fourth pair of pinion bores 110, 112, 114, and 116, respectively.The pinion bores 110-116 are formed in raised hub segments 120 of themain body 46. The pinion bores 110-116 are arranged in paired sets suchthat they communicate with each other and with the internal chamber 48.In addition, the pinion bores 110-116 are aligned substantially parallelto the rotational axis A of the axle shafts 44 and 45 (FIG. 1). A windowopening 124 may be arranged on the differential casing 40 between thefirst and the fourth pair of pinion gears 100 and 106.

With reference now to FIG. 5, the spacial relationship of the pinionpairs will be described. The four pinion bores 110-116, and as a result,the four pinion pairs 100-106 (FIG. 3), are radially spaced evenlyaround the differential casing 40 opposite the window opening 124. Morespecifically, the first pair of pinion bores 110 are offset a radialdistance a₁ from the second pair of pinion bores 112. The second pair ofpinion bores 112 are offset a radial distance a₂ from the third pair ofpinion bores 114. The third pair of pinion bores 114 are offset a radialdistance a₃from the fourth pair of pinion bores 116. As illustrated, therespective a distances are taken from the centerline of respective firstbores 110 a-110 d. The radial offsets between the pinion bores 110 and112, 112 and 114, and 114 and 116 may be approximately equivalent (e.g.,a₁=a₂=a₃). In the example provided, a₁, a₂ and a₃ are approximately 75degrees.

With specific reference now to FIGS. 2 b, 4 and 6, the configuration ofthe window opening 124 and the cooperation of the cross pin assembly 90will be described. The window opening 124 includes an access passage 126surrounded by a cylindrical boss 128 that may be formed on an outersurface 130 of the differential casing 40. The cylindrical boss 128defines a counterbore 132 having an inner radial engaging surface 136.The cylindrical boss 128 includes a pair of mounting passages 140 formedon raised flanges 142 for receiving a fastener 146 (FIG. 8)therethrough. A ledge portion 150 extends at least partially about thewindow opening 124 inwardly of the cylindrical boss 128 on thedifferential casing 40.

The cross pin assembly 90 generally includes a proximal head portion154, an intermediate shank portion 158 and a distal end portion 162. Thehead portion 154 defines a body that may extend generally transverse tothe longitudinal axis of the cross pin assembly 90. The head portion 154may include a throughbore 164 for receiving the fastener 146. The headportion 154 may include arcuate ends 168 that may be slidably disposedagainst the inner radial engaging surface 136 of the counterbore 132during assembly. A bottom surface 170 of the head portion 154 locatesagainst the ledge 150. The distal end portion 162 of the cross pinassembly 90 locates into a bore 172 formed into incorporated on thedifferential casing 40.

The cross pin assembly 90 may be unitarily formed or may comprise two ormore components. In the example provided, the cross pin assembly 90 is atwo-piece assembly comprising the proximal head portion 154, which maybe pressed onto a discrete shank that defines both the intermediateshank portion 158 and the distal end portion 162. It is appreciated thatwhile the distal end portion 162 of the cross pin assembly 90 is shownstepped down from the intermediate shank portion 158, the cross pinassembly 90 may comprise a uniform outer diameter. For example, analternate pinion gear arrangement may be employed with a differentialassembly providing enough space to accommodate a cross pin defining aconsistent outer diameter.

With reference to FIGS. 4 and 7, assembly of the cross pin assembly 90into the differential casing 40 will now be described in greater detail.Once the C-clips 94 are properly located and the spacer 86 is locatedbetween the side gears 66 a and 66 b, the spacer passage 92 may bealigned opposite the window opening 124 on the differential casing 40.The distal end 162 and the intermediate portion 158 of the cross pinassembly 90 are inserted through the window opening 124 and the spacerpassage 92. The distal end 162 of the cross pin assembly 90 may belocated into the bore 172 on the differential case 40 opposite thewindow opening 124. The bore 172 and the counterbore 132 pilot the crosspin assembly 90 during installation. The proximal head portion 154 maybe inserted in an orientation substantially transverse to the axis A ofthe differential casing 40. In this way, the head portion 154 of thecross pin assembly 90 will not interfere with the adjacent ring gear 38(FIG. 1) during installation.

As the distal end 162 of the cross pin assembly 90 locates into the bore172, the bottom surface 170 of the head portion 154 engages the ledge150 between the counterbore 132 and the window opening 124. Similarly,the arcuate ends 168 of the proximal head 154 engage the inner radialengaging surface 136 of the counterbore 132. The proximal head portion154 may then be rotated from the position shown in FIG. 7 into asubstantially parallel orientation with the axis A of the differential26 as illustrated in FIG. 8 until the throughbore 164 aligns with themounting passages 140 of the raised flanges 142 on the cylindrical boss128. During rotation of the proximal head portion 154, the inner radialengaging surface 136 pilots the arcuate ends 168 of the proximal headportion 154. Concurrently, the ledge 150 maintains the cross pinassembly 90 at the proper depth and assures that the throughbore 164will be properly aligned with the mounting passages 140 of the raisedflanges 142 on the cylindrical boss 128.

With the throughbore 164 and the mounting passages 140 aligned to oneanother, the fastener 146 may be inserted and secured. With the crosspin assembly 90 thus installed, relative movement between the cross pinassembly 90 and the differential casing 40 is essentially inhibited. Asa result, the endplay of the axle shafts 44 and 45 (FIG. 1) may becontrolled within desirable tolerances as a function of the diameter ofthe intermediate portion 158 of the cross pin assembly 90. The spacer 86is disposed between the sidegears 68 a and 68 b and controls axialendplay of the sidegears 68 a and 68 b to keep the differential 26 frombinding. The cross pin assembly 90 does not touch the spacer 86 in anassembled condition. The passage 92 in the spacer 86 defines a greaterdiameter than the diameter of the cross pin assembly 90. In this way,two distinct components are used to control the side gear endplay(namely, the spacer 86), and the axle shaft endplay (namely, the crosspin assembly 90). Such an arrangement allows for a desired amount ofside gear endplay without affecting the axle shaft endplay.

The mass of the differential assembly 26 may be distributed to providerotational balance. Specifically, the mass of the cylindrical boss 128and the cross pin head 154 cooperate with the mass of the differentialcasing 40 around the pinion bores 110-116 and the mass of the piniongears 100-106 to provide a rotationally balanced differential assembly26. Stated another way, the mass of the several components of thedifferential assembly 26 is distributed about the rotational axis A soas to minimize or eliminate imbalance when the differential assembly 26is rotated about the rotational axis A. It is appreciated that a counterweight may additionally, or alternatively be incorporated onto thedifferential casing 40 or the end cap 50 of the differential assembly26.

The fastener 146 may be configured the same as an open differential suchthat the same axle assembly lines may be ran with both opendifferentials and helical gear differentials without changing tooling ortorque wrench settings.

Turning now to FIG. 9, a differential assembly 226 according to otherfeatures is shown. The differential assembly 226 incorporates likecomponents as the differential assembly 26 which are identified with a200 prefix. The differential assembly 226 includes a cross pin 290having an intermediate shank portion 258 and a distal end portion 262.The cross pin 290 may be adapted to be retained in the differential case240 by a retaining disk 234. Specifically, the proximal end of the crosspin 290 may be adapted to recess into a counterbore 238 formed on aninboard surface of the retaining disk 234. A retaining ring 244 may beadapted to seat into a radial lip 248 arranged on the counterbore 232 inan assembled position.

With reference now to FIG. 10, a differential assembly 326 according toadditional features is shown. The differential assembly 326 incorporateslike components as the differential assembly 26 which are identifiedwith a 300 prefix. The differential assembly 326 includes a cross pin390 having an intermediate shank portion 358 and a distal end portion362. The cross pin 390 may be adapted to be retained in the differentialcase 340 by an L-plate 334 and a fastener 341. Specifically, a proximalend of the cross pin 390 may be adapted to pass through an opening 338arranged on the L-plate 334. In this way, the L-plate 334 cooperateswith the cross pin 390 to maintain the cross pin 390 in a substantiallyperpendicular orientation with axis A. The fastener 341 may be adaptedto be secured through passages 348 incorporated in flange portions 332and a passage 335 arranged in the L-plate 334. As a result, in aninstalled position, the fastener 341 bounds the proximal end of thecross pin 390 and maintains the cross pin 390 in an installed position.

With reference now to FIG. 11, a differential assembly 426 according toadditional features is shown. The differential assembly 426 incorporateslike components as the differential assembly 26 which are identifiedwith a 400 prefix. The differential assembly 426 includes a cross pin490 having an intermediate shank portion 458 and a distal end portion462. The cross pin 490 may be adapted to be retained in the differentialcasing 440 by a fastener 441. Specifically, the fastener 441 may beadapted to be secured through passages 448 incorporated in flangeportions 432 and a passage 435 arranged in the cross pin 490.

An access passage 426 may be incorporated in the differential casing 440and defines an access for installing C-clips 92 (FIG. 3). A spacer 486according to additional features includes a passage 492 for acceptingthe cross pin 490 therethrough in an assembled position. The spacer 486may be adapted to be installed into the differential casing 440 axiallyand be positioned between side gears as described herein.

While the disclosure has been described in the specification andillustrated in the drawings with reference to various embodiments, itwill be understood by those skilled in the art that various changes maybe made and equivalents may be substituted for elements thereof withoutdeparting from the scope of the disclosure as defined in the claims.Furthermore, the mixing and matching of features, elements and/orfunctions between various embodiments is expressly contemplated hereinso that one of ordinary skill in the art would appreciate from thisdisclosure that features, elements and/or functions of one embodimentmay be incorporated into another embodiment as appropriate, unlessdescribed otherwise, above. Moreover, many modifications may be made toadapt a particular situation or material to the teachings of thedisclosure without departing from the essential scope thereof.Therefore, it is intended that the disclosure not be limited to theparticular embodiment illustrated by the drawings and described in thespecification as the best mode presently contemplated for carrying outthis disclosure, but that the disclosure will include any embodimentsfalling within the foregoing description and the appended claims.

1. A differential assembly for a vehicle equipped with axle shafts, thedifferential assembly comprising: a differential casing rotatable aboutan axis, the differential casing including a first pin aperture having aledge; a ring gear fixed to the differential casing; a pair of sidegears disposed within the differential casing and adapted to drivinglyengage the axle shafts; a spacer disposed between the side gears, thespacer having a second pin aperture; and a cross pin having a body and atransversely extending head, the body being received into the first andsecond pin apertures, wherein the transversely extending head ispositioned at a first orientation during receipt of the cross pin intothe first pin aperture to clear the ring gear, the head engaging theledge to limit axial movement of the cross pin relative to thedifferential casing, the transversely extending head being rotated to asecond orientation when coupled to the differential casing; wherein thecross pin is adapted to limit movement of the axle shafts in a directiontoward one another and the spacer limits movement of the side gearstoward one another.
 2. The differential assembly of claim 1, wherein thefirst orientation and the second orientation differ by approximately 90degrees.
 3. The differential assembly of claim 2, wherein an end of thecross pin opposite the transversely extending head is received inanother aperture formed in the differential casing.
 4. The differentialassembly of claim 1, wherein a threaded fastener removably couples thecross pin to the differential casing and extends substantiallyperpendicular to an axis of insertion of the cross pin within thedifferential casing.
 5. The differential assembly of claim 4, whereinthe differential casing includes radially extending spaced apart flangeshaving apertures in receipt of the threaded fastener.
 6. Thedifferential assembly of claim 1, wherein the spacer is substantially“U-shaped.”
 7. A differential assembly for a vehicle having axle shafts,comprising: a differential casing rotatable about an axis, thedifferential casing including a first aperture defined by twodiscontinuous arced surfaces and two slots, each slot being incommunication with an end of each arced surface; a pair of side gearsdisposed within the differential casing; a spacer disposed between theside gears, the spacer having a second aperture; and a cross pinreceived by the first and second apertures; wherein the cross pin isengaged with the two arced surfaces and fixedly but removably coupled tothe differential casing, wherein the slots are sized to receive clipsadapted to restrict axial movement of the axle shafts relative to thedifferential casing.
 8. The differential assembly of claim 7, furtherincluding a fastener extending through an aperture formed in the crosspin and engaged with the differential casing.
 9. The differentialassembly of claim 8, wherein the differential casing includes radiallyextending spaced apart flanges having apertures in receipt of thefastener.
 10. The differential assembly of claim 9, wherein thefasteners extend along an axis substantially parallel to the axis ofrotation of the differential casing.
 11. The differential assembly ofclaim 7, wherein one end of the cross pin is received by the firstaperture and a second end of the cross pin is received in anotheraperture formed in the differential casing.
 12. The differentialassembly of claim 7, wherein a common uninterrupted sidewall defines anouter periphery of the two slots and the two arced surfaces.
 13. Adifferential assembly for a vehicle equipped with axle shafts, thedifferential assembly comprising: a differential casing rotatable aboutan axis, the differential casing including a counterbore having a ledge;a pair of side gears disposed within the differential casing and adaptedto drivingly engage the axle shafts; a spacer disposed between the sidegears, the spacer having a pin aperture; a cross pin received into thecounterbore and the pin aperture, and a retaining disk having a recessin receipt of a first end of the cross pin, the retaining disk engagingthe ledge and being removably fixed to the differential casing by afastener.
 14. The differential assembly of claim 13, wherein the crosspin is spaced apart from the differential casing.
 15. The differentialassembly of claim 13, wherein the fastener is a ring retaining the diskwithin the counterbore.
 16. The differential assembly of claim 13,wherein a second end of the cross pin is received within an apertureformed in the differential casing.